Deck 19: Nuclear Chemistry

Question 1

When atoms of beryllium-9 are bombarded with alpha particles, neutrons are produced. What new isotope is also formed
${ }_{2}^{4} \mathrm{He}+{ }_{4}^{9} \mathrm{Be} \rightarrow{ }_{0}^{1} \mathrm{n}+\_\_\_\_\_\_$

A) ${ }_{6}^{12} \mathrm{C}$
B) ${ }_{3}^{5} \mathrm{Li}$
C) ${ }_{3}^{8} \mathrm{Li}$
D) ${ }_{5}^{10} \mathrm{~B}$
E) ${ }_{5}^{12} \mathrm{~B}$

Answer 1

${ }_{6}^{12} \mathrm{C}$

Question 2

Alpha particles are identical to

A) protons.
B) helium atoms.
C) hydrogen atoms.
D) helium nuclei.
E) electrons.

Answer 2

helium nuclei.

Question 3

Consider the following decay series: What is the symbol for the product labeled as Y

A) ${ }_{84}^{126} \mathrm{Po}$
B) ${ }_{83}^{127} \mathrm{Bi}$
C) ${ }_{82}^{124} \mathrm{~Pb}$
D) ${ }_{84}^{210} \mathrm{Po}$
E) ${ }_{82}^{206} \mathrm{~Pb}$

Answer 3

${ }_{82}^{124} \mathrm{~Pb}$

Question 4

Sulfur-35 decays by beta emission. The decay product is

A) ${ }_{15}^{35} \mathrm{P}$
B) ${ }_{16}^{34} \mathrm{~S}$
C) ${ }_{30}^{31} \mathrm{Si}$
D) ${ }_{17}^{34} \mathrm{Cl}$
E) ${ }_{17}^{35} \mathrm{Cl}$

Question 5

Which of the following is characteristic of a nuclear reaction
I. Electrons in atomic orbitals are involved in the breaking and forming of bonds
II. Elements are converted from one to another
III. Reaction rates are typically not affected by catalysts
IV. Atoms are rearranged by the breaking and forming of chemical bonds

A) I and II
B) I, II, and III
C) III and IV
D) II and III
E) I, II, III, and IV

Question 6

Consider the following decay series: What type of nuclear process occurs at the transformation labeled I

A) aemission
B) bemission
C) positron emission
D) electron capture
E) gamma radiation

Question 7

List the number of protons, neutrons, and nucleons (protons + neutrons), in that order, for an isotope with the symbol: $^{137}_{~~55}$ Cs

A) 137, 55, 192
B) 55, 137, 192
C) 55, 82, 137
D) 82, 55, 137
E) 82, 137, 219

Question 8

Consider the following decay series: What type of nuclear process occurs at the transformation labeled II

A) aemission
B) bemission
C) positron emission
D) electron capture
E) gamma radiation

Question 9

Which of the following represents a rule for balancing a nuclear equation
I. The total number of protons plus neutrons in the products and reactants must be the same
II. The total number of each type of element in the products and reactants must be the same
III. The total number of nuclear charges in the products and reactants must be the same
IV. The total number of each type of elementary particle in the products and reactants must be the same

A) I, II, III, and IV
B) I, II, and IV
C) I, III, and IV
D) III and IV
E) I and III

Question 10

As a result of beta decay, the product nucleus is

A) one atomic number lower than the original element.
B) two atomic numbers higher than the original element.
C) one atomic number higher than the original element.
D) two atomic numbers lower than the original element.
E) four atomic numbers lower than the original element.

Question 11

The only stable isotope of iodine is iodine-127. Predict the mode of decay of ${ }_{53}^{130} \mathrm{I}$

A) alpha emission
B) beta emission
C) positron emission
D) electron capture

Question 12

Beta particles are identical to

A) protons.
B) helium atoms.
C) hydrogen atoms.
D) helium nuclei.
E) electrons.

Question 13

Consider the following decay series: What is the complete element symbol for the product labeled Y

A) ${ }_{83}^{127} \mathrm{Bi}$
B) ${ }_{82}^{128} \mathrm{~Pb}$
C) ${ }_{83}^{210} \mathrm{Bi}$
D) ${ }_{82}^{210} \mathrm{~Pb}$
E) ${ }_{84}^{210} \mathrm{Po}$

Question 14

As a result of alpha emission, the product nucleus is

A) one atomic number lower than the original element.
B) two atomic numbers higher than the original element.
C) one atomic number higher than the original element.
D) two atomic numbers lower than the original element.
E) four atomic numbers lower than the original element.

Question 15

Consider the following decay series: ${ }_{84}^{218} \mathrm{Po} \xrightarrow{\mathrm{a}}{ }_{82}^{214} \mathrm{~Pb} \xrightarrow{\mathrm{~b}}{ }_{83}^{214} \mathrm{Bi} \xrightarrow{\mathrm{c}}{ }_{84}^{214} \mathrm{Po} \xrightarrow{\mathrm{~d}}{ }_{82}^{210} \mathrm{~Pb}$ Which type of nuclear process occurs in steps a and b, respectively

A) aemission, a emission
B) aemission, b emission
C) bemission, positron emission
D) bemission, a emission
E) positron emission, b emission

Question 16

Consider the following decay series: What type of nuclear process occurs at the transformation labeled I

A) aemission
B) bemission
C) positron emission
D) electron capture
E) gamma radiation

Question 17

List the number of protons, neutrons, and nucleons (protons + neutrons), in that order, for an isotope with the symbol: $^{137}_{~~56}$ Ba

A) 56, 81, 137
B) 81, 56, 137
C) 56, 137, 193
D) 137, 56, 193
E) 81, 137, 218

Question 18

Consider the following decay series: ${ }_{84}^{218} \mathrm{Po} \xrightarrow{\mathrm{a}}{ }_{82}^{214} \mathrm{~Pb} \xrightarrow{\mathrm{~b}}{ }_{83}^{214} \mathrm{Bi} \xrightarrow{\mathrm{c}}{ }_{84}^{214} \mathrm{Po} \xrightarrow{\mathrm{~d}}{ }_{82}^{210} \mathrm{~Pb}$ Which type of nuclear process occurs in steps c and d, respectively

A) aemission, a emission
B) aemission, b emission
C) bemission, positron emission
D) bemission, a emission
E) positron emission, b emission

Question 19

Consider the following decay series: What type of nuclear process occurs at the transformation labeled II

A) aemission
B) bemission
C) positron emission
D) electron capture
E) gamma radiation

Question 20

Radium-226 decays by alpha emission. What is its decay product

A) ${ }_{87}^{228} \mathrm{Fr}$
B) ${ }_{86}^{222} \mathrm{Rn}$
C) ${ }_{90}^{230} \mathrm{Th}$
D) ${ }_{89}^{226} \mathrm{Ac}$
E) ${ }_{84}^{224} \mathrm{Po}$

Question 21

What fraction of radioactive atoms remains in a sample after six half-lives

A) zero
B) 1/6
C) 1/16
D) 1/32
E) 1/64

Question 22

1 joule equals

A) 1 kg m
B) 1 g m² s²
C) 1 kg m²/s
D) 1 g m²/s
E) 1 kg m²/s²

Question 23

Which of the following nuclear processes results in an increase of atomic number in the product element formed
I. Alpha emission
II. Beta emission
III. Positron emission
IV. Electron capture

A) I and II
B) III and IV
C) I, II, and III
D) II only
E) IV only

Question 24

The energy equivalent of a mass defect of - 0.1710 amu is which of the following

A) - 5.130 x 10⁷ J
B) - 1.539 x 10¹⁶ J
C) - 2.556 x 10^-8 J
D) - 2.556 x 10^-11 J
E) - 8.519 x 10^-20 J

Question 25

The energy equivalent of a mass defect of - 0.1620 amu is which of the following

A) - 1.458 x 10¹⁶ J
B) - 2.421 x 10^-8 J
C) - 2.421 x 10^-11 J
D) - 2.421 x 10¹³ J
E) - 1.458 x 10^-11 J

Question 26

Determine how much energy is released when polonium-210 decays according to ${ }^{210} \mathrm{Po} \rightarrow{ }^{4} \mathrm{He}+{ }^{206} \mathrm{~Pb}$ . [Atomic masses: polonium-210 = 209.982857 amu; helium-4 = 4.002603 amu; lead-206 = 205.974449 amu]

A) 4.14 * 10⁹ kJ/mol
B) 7.20 * 10¹¹ kJ/mol
C) 5.22 * 10⁸ kJ/mol
D) 4.66 * 10⁹ kJ/mol
E) 6.43 * 10¹² kJ/mol

Question 27

Find the nuclear binding energy of uranium-234 (atomic mass = 234.040947 amu) in units of joules per nucleon. [Data: neutron mass = 1.674928 * 10^-24 g; proton mass = 1.672623 * 10^-24 g; electron mass = 9.109387 * 10^-28 g; N_A = 6.0221367 * 10²³ /mol; c = 2.99792458 * 10⁸ m/s]

A) 2.97 * 10^-10 J/nucleon
B) 1.22 * 10^-12 J/nucleon
C) 3.04 * 10^-10 J/nucleon
D) 1.30 * 10^-12 J/nucleon
E) 1.41 * 10^-12 J/nucleon
F) 1.27 * 10^-12 J/nucleon

Question 28

What is the nuclear binding energy per nucleon, in joules, for ${ }_{12}^{25} \mathrm{Mg}$ (atomic mass 24.985839 amu)
[Data: ${ }_{1}^{1} \mathrm{H}$ (atomic mass) = 1.007825 amu; ${ }_{0}^{1} \mathrm{n}$ (mass) = 1.008665 amu; 1 kg = 6.022 * 10²⁶ amu; c = 3.00 * 10⁸ m/s]

A) 0.22076 J/nucleon
B) 3.30 * 10^-11 J/nucleon
C) 1.32 * 10^-12 J/nucleon
D) 0.999 J/nucleon
E) None of the above.

Question 29

Which of the following nuclear processes does not change the mass number in the product element formed
I. Alpha emission
II. Beta emission
III. Positron emission
IV. Electron capture

A) I and II
B) III and IV
C) I, II, and III
D) II, III, and IV
E) IV only

Question 30

A balanced nuclear equation representing the alpha emission of curium-242 is which of the following

A) ${ }_{96}^{242} \mathrm{Cm}+{ }_{2}^{4} \mathrm{He} \longrightarrow{ }_{94}^{246} \mathrm{Pu}$
B) ${ }_{96}^{242} \mathrm{Cm} \longrightarrow{ }_{98}^{246} \mathrm{Cf}+{ }_{2}^{4} \mathrm{He}$
C) ${ }_{96}^{242} \mathrm{Cm} \longrightarrow{ }_{94}^{238} \mathrm{Pu}+{ }_{2}^{4} \mathrm{He}$
D) ${ }_{96}^{242} \mathrm{Cm}+{ }_{2}^{4} \mathrm{He} \longrightarrow{ }_{98}^{246} \mathrm{Cf}$
E) ${ }_{96}^{242} \mathrm{Cm} \longrightarrow{ }_{97}^{242} \mathrm{Bk}+{ }_{-1}^{0} \alpha$

Question 31

Determine how much energy is released when thorium-230 decays according to ${ }^{230} \mathrm{Th} \rightarrow{ }^{4} \mathrm{He}+{ }^{226} \mathrm{Ra}$ . [Atomic masses: thorium-230 = 230.033127 amu; helium-4 = 4.002603 amu; radium-226 = 226.025403 amu]

A) 3.98 * 10⁹ kJ/mol
B) 4.60 * 10⁸ kJ/mol
C) 7.20 * 10¹¹ kJ/mol
D) 4.90 * 10⁹ kJ/mol
E) 7.15 * 10¹¹ kJ/mol

Question 32

Calculate the energy released in joules when one mole of polonium-214 decays according to the equation ${ }_{84}^{214} \mathrm{Po} \rightarrow{ }_{82}^{210} \mathrm{~Pb}+{ }_{2}^{4} \mathrm{He} .$ [Atomic masses: Pb-210 = 209.98284 amu, Po-214 = 213.99519 amu, He-4 = 4.00260 amu.]

A) 8.78 * 10¹⁴ J/mol
B) 7.2 * 10¹⁴ J/mol
C) 8.78 * 10¹¹ J/mol
D) -9.75 * 10^-3 J/mol
E) 1.46 * 10^-9 J/mol

Question 33

What fraction of radioactive atoms remains in a sample after five half-lives

A) zero
B) 1/6
C) 1/16
D) 1/32
E) 1/64

Question 34

A balanced nuclear equation representing the beta emission of iodine-131 is which of the following

A) ${ }_{53}^{131} \text{I} \longrightarrow{ }_{54}^{131} \mathrm{Xe}+{ }_{-1}^{0} \beta$
B) ${ }_{53}^{131} \mathrm{I} \longrightarrow{ }_{51}^{127} \mathrm{Sb}+{ }_{2}^{4} \mathrm{He}$
C) ${ }_{53}^{131} \mathrm{I}+{ }_{-1}^{0} \beta \longrightarrow{ }_{52}^{131} \mathrm{Te}$
D) ${ }_{53}^{131} \mathrm{I} \longrightarrow{ }_{52}^{131} \mathrm{Te}+{ }_{+1}^{0} \beta$
E) ${ }_{53}^{131} \mathrm{I}+{ }_{-1}^{0} \mathrm{e} \longrightarrow{ }_{52}^{131} \mathrm{Te}$

Question 35

The isotope with the greatest nuclear binding energy per nucleon is

A) ${ }_{1}^{2} \mathrm{H}$
B) ${ }^{4} \mathrm{He}$
C) ${ }_{6}^{14} \mathrm{C}$
D) ${ }_{26}^{56} \mathrm{Fe}$
E) ${ }_{92}^{238} \mathrm{U}$

Question 36

Carbon-11 is a radioactive isotope of carbon. Its half-life is 20.3 minutes. What fraction of the initial number of carbon-11 atoms in a sample will remain after 81 minutes

A) 1/16
B) 1/4
C) 1/2
D) 1/32
E) 1/8

Question 37

The only stable isotope of aluminum is aluminum-27. What type of radioactive decay should be expected from ${ }_{13}^{28} \mathrm{Al}$

A) ${ }_{1}^{1} \mathrm{H}$
B) ${ }_{0}^{1} \text{n}$
C) ${ }_{-1}^{~~~0} \beta$
D) ${ }_{+1}^{~~~0} \beta$
E) ${ }_{2}^{4} \mathrm{He}$

Question 38

Find the nuclear binding energy of potassium-40 (atomic mass = 39.9632591 amu) in units of joules per nucleon. [Data: neutron mass = 1.674928 * 10^-24 g; proton mass = 1.672623 * 10^-24g; electron mass = 9.109387 * 10^-28 g; N_A = 6.0221367 * 10²³ /mol; c = 2.99792458 * 10⁸ m/s]

A) 1.37 * 10^-12 J/nucleon
B) 5.48 * 10^-11 J/nucleon
C) 5.64 * 10^-11 J/nucleon
D) 1.41 * 10^-12 J/nucleon
E) 2.97 * 10^-12 J/nucleon

Question 39

A typical radius of an atomic nucleus is about

A) 100 µm
B) 5000 mm
C) 100 nm
D) 5 * 10^-3 pm
E) 500 pm

Question 40

Which of the following nuclear processes results in an increase in the number of neutrons in the product element
I. Alpha emission
II. Beta emission
III. Positron emission
IV. Electron capture

A) I and II
B) III and IV
C) I, II, and III
D) II, III, and IV
E) I, II, III, and IV

Question 41

What would the atom ratio of ²⁰⁶Pb to ²³⁸U be in a uranium mineral from a rock that is 1.0 * 10⁹ years old? t_1/2(²³⁸U) = 4.5 * 10⁹ yr.

A) 0.14
B) 0.16
C) 0.22
D) 0.86
E) 1.16

Question 42

The heaviest known isotope of hydrogen is called tritium, $^3_1$ H . It decays by beta emission, and has a half-life of 12.3 years. What fraction of a tritium sample will remain after 5.20 years

A) 0.0210
B) 0.746
C) 3.41
D) 0.254
E) 0.423

Question 43

The half-life of ⁹⁰Sr is 29 years. What fraction of the atoms in a sample of ⁹⁰Sr would remain 175 years later

A) 0.17
B) 0.12
C) 0.062
D) 0.015
E) 0.50

Question 44

In passing through matter, alpha particles lose energy chiefly by causing

A) fermentation.
B) neutralization.
C) ionization.
D) condensation.
E) carbonation.

Question 45

Cobalt-60 is a beta emitter with a half-life of 5.3 years. Approximately what fraction of the cobalt-60 atoms in a particular sample will remain after 32 years

A) 1/6
B) 1/8
C) 1/16
D) 1/32
E) 1/64

Question 46

The energy released by the sun is the result of

A) natural radioactivity.
B) nuclear fusion.
C) combustion of hydrogen.
D) photosynthesis.
E) nuclear fission.

Question 47

The radioisotope potassium-40 decays to argon-40 by positron emission with a half-life of 1.3 * 10⁹ yr. A sample of moon rock was found to contain 78 argon-40 atoms for every 22 potassium-40 atoms. The age of the rock is

A) 8.1 * 10^-10 yr.
B) 2.4 * 10⁹ yr.
C) 2.8 * 10⁹ yr.
D) 4.6 * 10⁹ yr.
E) 6.8 * 10⁹ yr.

Question 48

Charcoal found under a stone at Stonehenge, England, has a carbon-14 activity that is 0.60 that of new wood. How old is the charcoal (The half-life of carbon-14 is 5,730 years.)

A) Less than 5,730 yr
B) Between 5,730 and 11,460 yr
C) Between 11,460 and 17,190 yr
D) More than 17,190 yr

Question 49

A rock contains 0.37 mg of Pb-206 and 0.95 mg of U-238. The half-life of the decay series U-238 $\rarr$ Pb-206 is 4.5 * 10⁹ yr. Assuming no Pb-206 was present in the rock initially, how old is the rock

A) 1.7 * 10⁹ yr
B) 5.2 * 10⁹ yr
C) 2.7 * 10⁶ yr
D) 4.5 * 10⁹ yr
E) 2.4 * 10⁹ yr

Question 50

The Rb-87/Sr-87 method of dating rocks is often used by geologists: ${ }_{37}^{87} \mathrm{Rb} \rightarrow{ }_{38}^{87} \mathrm{Sr}+{ }_{-1}^{0} \mathrm{\beta}$ t_1/2 = 6.0 * 10¹⁰ yr.Estimate the age of a rock sample in which the present-day mole ratio of Rb-87 to Sr-87 is 36:1.

A) 2.4 * 10⁹ yr
B) 1.7 * 10⁹ yr
C) 3.1 * 10¹¹ yr
D) 4.1 * 10^-11 yr
E) 3.6 * 10¹¹ yr

Question 51

If 24% of a certain radioisotope decays in 6.5 years, what is the half-life of this isotope

A) 3.9 yr
B) 16 yr
C) 0.22 yr
D) 2.2 yr
E) 3.2 yr

Question 52

A rock contains 0.37 mg of Pb-206 and 0.95 mg of U-238. Approximately how many U-238 atoms were in the rock when it was formed billions of years ago (The half life for ²³⁸U $\rarr$ ²⁰⁶Pb is 4.5 * 10⁹ yr.)

A) 1.32 atoms
B) 5.8 * 10^-6 atoms
C) 2.4 * 10¹⁸ atoms
D) 3.5 * 10¹⁸ atoms
E) 3.5 * 10²¹ atoms

Question 53

How old is a bottle of wine if the tritium (³H) content is 25% that of a new wine? The half-life of tritium is 12.5 years.

A) 0.25 yr
B) 3.1 yr
C) 25 yr
D) 38 yr
E) 50. yr

Question 54

Cobalt-60 is a beta emitter with a half-life of 5.3 years. Approximately what fraction of cobalt-60 atoms will remain in a particular sample after 26.5 years

A) 1/5
B) 1/16
C) 1/26
D) 1/32
E) 1/64

Question 55

Which type of nuclear process requires an extremely high temperature (millions of degrees)

A) beta decay
B) fission reaction
C) fusion reaction
D) alpha decay
E) positron emission

Question 56

What role does cadmium metal (Cd) play in a nuclear reactor

A) slows down the fission neutrons (moderator)
B) transfers heat from the reactor to the heat exchanger (primary coolant)
C) controls chain reaction (control rods)
D) transfers heat from the condenser to the environment (cooling tower)
E) undergoes fission (fuel rods)

Question 57

Which one of the following statements about fission and fusion is false

A) Fission occurs among the heaviest isotopes, whereas fusion occurs more readily for light isotopes.
B) For a fission reaction the mass defect (Dm) is negative, whereas for fusion Dm is positive.
C) In order for fusion reactions to occur, temperatures must be in the millions of degrees.
D) The fission of Pu-239 atoms produces a great number of isotopes of a large number of elements.
E) Neutron-induced fission processes can occur at room temperature, rather than at millions of degrees.

Question 58

If 12% of a certain radioisotope decays in 5.2 years, what is the half-life of this isotope

A) 0.59 yr
B) 1.7 yr
C) 22 yr
D) 28 yr
E) 32 yr

Question 59

Estimate the age of a bottled wine that has a tritium, ³H, content 60% that of freshly bottled wine. Tritium decays by beta decay and has a half-life of 12.3 yr. ${ }_{1}^{3} \mathrm{H} \rightarrow{ }_{2}^{3} \mathrm{He}+{ }_{-1}^{0} \mathrm{\beta}$

A) 0.029 yr
B) 7.4 yr
C) 9.1 yr
D) 16 yr
E) 35 yr

Question 60

Polonium-208 is an alpha emitter with a half-life of 2.90 years. How many milligrams of polonium from an original sample of 2.00 mg will remain after 8.00 years

A) 0.147 mg
B) 0.296 mg
C) 0.725 mg
D) 6.77 mg
E) 1.90 mg

Question 61

Which isotope, when bombarded with nitrogen-15, yields the artificial isotope dubnium-260 plus 4 neutrons

A) californium-245
B) thorium-257
C) nobelium-245
D) californium-249
E) dubnium-249

Question 62

Present-day plant life has a carbon-14 decay rate of 16 disintegrations per minute (dpm) per gram of carbon. If a contemporary wooden chair were somehow preserved for the next 3,900 years, what ¹⁴C decay rate should be expected from the wood used to make the chair (t_1/2 = 5,730 yr)

A) 26 dpm
B) 12 dpm
C) 11 dpm
D) 10 dpm
E) 8 dpm

Question 63

In the following reaction, identify X . ${ }_{98}^{252} \mathrm{Cf}\left({ }^{10} \mathrm{~B}, 5 \mathrm{n}\right) \mathrm{X}$

A) ${ }_{103}^{257} \mathrm{Lr}$
B) ${ }_{98}^{247} \mathrm{~Np}$
C) ${ }_{98}^{247} \mathrm{Cf}$
D) ${ }_{103}^{262} \mathrm{Lr}$
E) ${ }_{93}^{257} \mathrm{~Np}$

Question 64

The dose unit of ionizing radiation is called the rad. The rad is defined in terms of

A) the half-life of a radioisotope.
B) the energy deposited per gram of an object.
C) the biological damage produced.
D) the accumulation of fission products.
E) the number of ions per centimeter.

Question 65

How many ¹⁴C atoms are in a charcoal sample that has a decay rate of 3,500 disintegrations per min? (For ¹⁴C, t_1/2 = 5,730 yr.)

A) 2.9 * 10⁷ atoms
B) 8.0 * 10^-7 atoms
C) 1.4 * 10¹⁴ atoms
D) 1.5 * 10¹³ atoms
E) 6.02 * 10²⁰ atoms

Question 66

Decay of lutetium-167 by electron capture yields

A) ytterbium-167.
B) lutetium-166.
C) thulium-163.
D) tantalum-171.
E) hafnium-167.

Question 67

Which isotope, when bombarded with oxygen-18, yields the artificial isotope seaborgium-263 plus 4 neutrons

A) nobelium-245
B) radium-259
C) californium-245
D) nobelium-249
E) californium-249

Question 68

List the different types of nuclear radiation (alpha, beta, gamma) in order of increasing penetrating power.

A) alpha < beta < gamma
B) beta < alpha < gamma
C) gamma < alpha < beta
D) gamma < beta < alpha
E) alpha < gamma < beta

Question 69

Which of the following is an example of a free radical

A) H₃O⁺
B) H₂O₂
C) HO₂^-
D) HO₂·
E) H₂O

Question 70

The carbon-14 activity of some ancient Indian corn was found to be 7.0 disintegrations per minute (dpm) per gram of carbon. If present-day plant life has 16 dpm per gram of carbon, how old is the Indian corn? (t_1/2 = 5,730 yr)

A) 6,800 yr
B) 2,500 yr
C) 4,700 yr
D) 10,000 yr
E) 7,200 yr

Question 71

The half-life of ¹⁴C is 5,730 yr. Assuming some charcoal from a campfire 29,000 years old was found, what fraction of the original C-14 would remain today

A) 3.0 * 10^-2
B) 0.197
C) 3.51
D) 33.3
E) None of these.

Question 72

List the given types of nuclear radiation (cosmic rays, medical and dental X rays, and nuclear waste) in order of how much each contributes to the average yearly dose of nuclear radiation for Americans

A) cosmic rays < medical and dental X rays < nuclear waste
B) medical and dental X rays < cosmic rays < nuclear waste
C) nuclear waste < cosmic rays < medical and dental X rays
D) cosmic rays < nuclear waste < medical and dental X rays
E) medical and dental X rays < nuclear waste < cosmic rays

Question 73

Gamma-rays cause radiation damage when they interact with matter by producing

A) ions and free radicals.
B) isotopes.
C) daughter products.
D) oxidation.
E) reduction.

Question 74

In the following reaction, identify X. ${ }_{92}^{238} \mathrm{U}(15 \mathrm{n}, \mathrm{X}){ }_{99}^{253} \mathrm{Es}$

A) 7b
B) 3a
C) 4n
D) $7_{+1}^{~~~0} \mathrm{e}$
E) 15p

Question 75

Decay of silicon-27 by positron emission yields

A) magnesium-23.
B) sulfur-31.
C) phosphorus-27.
D) silicon-26.
E) aluminum-27.

Question 76

In the following reaction, identify X. ${ }_{5}^{10} \mathrm{~B}(\mathrm{X}, \alpha){ }_{3}^{7} \mathrm{Li}$

A) a
B) n
C) p
D) $^{~~~0}_{+1}$ e
E) b

Question 77

Rubidium-87 decays by beta decay with a half-life of 4.9 * 10¹⁰ yr. How many ⁸⁷Rb atoms are in a moon rock sample that has a rubidium decay rate of 3,500 disintegrations per hour

A) 9.0 * 10¹⁶ atoms
B) 4.3 * 10^-4 atoms
C) 2.2 * 10¹⁸ atoms
D) 2.5 * 10¹⁴ atoms
E) 1.7 * 10¹⁴ atoms

Question 78

Decay of tin-110 by electron capture yields

A) tin-109.
B) cadmium-106.
C) indium-110.
D) antimony-110.
E) tellurium-114.

Question 79

Petroleum is a fossil fuel containing many different carbon compounds. If the carbon atoms in petroleum have been in the ground for 100 million years, what fraction of the initial ¹⁴C atoms is still there? (t_1/2 = 5,370 yr)

A) 0
B) 1 * 10^-10
C) 5.7 * 10^-5
D) 1.0 * 10^-3
E) 5.7 * 10^-1

Question 80

A sample of a radioisotope shows an activity of 999 disintegrations per minute due to beta decay. If after 1.10 years the activity is 952 disintegrations per minute, what is the half-life of this radioisotope

A) 4.38 * 10^-2 yr
B) 11.4 yr
C) 0.25 yr
D) 15.8 yr
E) 9.1 yr